I noticed a couple of things that were just inaccurate in your post which i felt the need to clarify
Maybe instead of doing such drastic changes so frequently maybe alter and change current things to make minor differences to the game.
The frequent drastic changes you mentioned are because of the 3 mid-season patches that were released in succession of each other, and for the most part riot was trying to see if releasing these changes in multiple patches rather than in one big one would be better(which it wasn't) and for the moment they have been following up with what you said looking at the new patch.
Also, if you stop mentioning how many people play this game or how well you are growing for players you might want to think about the direction this game is going. I have been playing this game since the end of season 2. I have been around for the long haul.
When is the last time they mentioned the player count on league, from my knowledge they havn't done so in years and they rarely talk about how well they grow their player base, but they are making changes to try and grow it; the new League ads, the new tutorial and missions that have been added.
What I am going to tell you is going to be hard. You are losing a lot of these veteran players who will take a large portion of your player base away for you from changing games.
I don't doubt veterans are going to leave the game but i am also going to guess that they are leaving to focus on their live because they have grown up from when they started playing and it was inevitable. Changing the game is one of the reasons this game has survived so long.
Streamers youtubers they don't like playing your game anymore. Most switch to Fortnite or other games. There's a reason. This game isn't what it used to be.
I am not really sure where you got your information because most of the streamers i watch quite enjoy the game with the exception of 1 being shaclone, I havn't seen that many streamers quit league for fortnite aside then nightblue but he came back so i'm not sure what you are trying to say here. Of course this game isn't what it used to be that's what happens when consistently change the game over 9 years.
You say you want change, yet when there are new methods to strategizing a way to win "funnel" maybe don't kill the idea right away.
The problem with the funneling strategy was that it was too oppressive and unfun for both teams while being very oppressive. Riot didn't kill it right away, they left it alone for around a month before nerfing it.
All I am saying is stop being so creative. Simple concepts for champs are way better. It's obvious that you are trying way to hard.
This is more just you opinion because that is not necessarily true for the player base, i prefer champion that require skill to play against not just avoid and ward but actual counterplay, i really like pyke as a champion and he has a lot of creative concepts that make him unique and enjoyable to play, while on the other champions like garen, lux, ahri, malphite who have very simple kits i don't find fun to play because they are too simple.
Btw if things continue in the direction they are going I am officially done playing and buying any products from you. You are not listening to anything people have to say.
Here is the thing about the playerbase, we are very split and all want different things with the game, but in the end it boils down to two groups that rotate in and out of the boards based on the state of the game. One the one side you have marksmans, enchanter supports and tanks. And on the other you have mage supports, assassins and bruisers, while mages are sprinkled between the 2 groups. During this meta group 2 is enjoying themselves and don't want the game to change anymore because the game is great for them therefor riot is listening to what this half of the players are saying, while on the otherhand during ardent censor meta it was the opposite and group 1 was enjoying themselves finding the game to be great and riot was listening to them until they listened to the other half, and that is an endless cycle.
We say get away from tank meta and its still here. We say get away from tank meta and you nerf attack damage carries. You nerfed them so hard that they arent even a role that can carry anymore.
We say get away from tank meta and we aren't in a tank meta at all, we are in assassins and bruisers rule all meta, both tanks and adc are very weak right now proving once again it isn't a tank meta because in a tank meta its those two classes that are the strongest.
You talk about how you want to reward the person that is playing well and having them be able to carry the game but its still whom ever has the worst player on their team loses. Who ever has the teammate that feeds the most loses. Is this fair when the rest of your team may go positive and win? And if you answer yes to that why would anyone want to play this game where they do well and still lose because of someone else? Rhetorical they won't hence the reason your player base is dropping.
Right now the only way a player on your team can single handedly lose you the game is if they either run it down or afk, aside from that there is a lot of carry potential, people who play well, will generelly win in this meta unless they are playing crit adc or a tank.